Liv Tyler has signed on to play Betty Ross, the lady love of Dr. Bruce Banner/the Hulk, played by Edward Norton in the next Incredible Hulk movie. Reuters continues:
Ross, a classic "Hulk" character from the comic book's beginning in 1962, is Banner's fellow scientist and an ally in his quest to rid him of his lurking monster deep inside. The movie will unfold with Ross estranged from Banner (Norton), but with the pursuit of the Hulk heating up and Banner on the run trying to cure his condition, Ross finds herself swept back into his life.
The last person to play Betty Ross in an Incredible Hulk movie was another dark-haired beauty Jennifer Connelly. So... Liv Tyler. Sure. Why not?